As is well known to any person skilled in the art, there are both axial and rotational movements between the rod or spindle and housing or barrel of a conventional rail vehicle slack adjuster of the axial type at each and every brake operation. This means that the required sealing between the rod and the housing is exposed to great wear, not the least in view of the extremely harsh environment underneath a rail vehicle, where the slack adjuster is mounted.
A very conventional sealing in the housing may consist of one or more internal sealing rings engaging the rod. These sealing rings may be made of a plastic material in order to withstand the wear better than rubber rings. The result is, however, not satisfactory in some instances when the sealing after a certain period of operation is not tight any more and allows water and contaminants to enter the interior of the slack adjuster resulting in rust problems and eventually function disturbances.
A solution to the above problems was presented in EP-B-353 796, to which reference is made for a full understanding.
The sealing arrangement proposed therein has been used in practice for a period of time and has generally speaking proved advantageous, especially with regard to the possibility for water or moist introduced in the cup in any way to leave it. However, a special problem is that the sealing arrangement is sometimes exposed to forceful water sprays, for example when the undercarriage of the vehicle is cleaned. Generally speaking, the object of the invention is to improve the ability of the sealing arrangement defined above to prevent the intrusion of water, moist, dirt and the like, whilst allowing water in the cup to leave it.